Most beverage cans presently produced in the United States are so-called "two-piece cans" which are typically made from aluminum. A two-piece can includes a can body which has a cylindrical side wall portion and an integrally formed bottom wall portion. The can body is open at the top, terminating in an annular peripheral flange portion. The second component of a two-piece can is a can "lid" or "closure" which is more commonly referred to in the industry as a can "end". The can end has an annular peripheral flange or "curl" portion which is seamed to a corresponding peripheral flange portion of the can body to seal the opening in the can body. The can end is seamed to the can body after the can body has been filled with the desired beverage. Can ends are typically formed in a series of die presses which initially form the basic can end configuration or "shell". Subsequently the shell has various operations performed thereon, such as embossing, debossing, scoring, rivet formation and tab staking, to complete the end. A can end press is described in U.S. Pat. No. 4,939,665 of Gold et al. issued Jul. 3, 1990 which is hereby incorporated by reference for all that it discloses.
Most can ends used in the packaging of beverages such as soft drinks and beer include a score panel. The score panel may be formed by a pair of closely spaced score lines which are provided in a generally ring-shaped configuration referred to herein as a "score profile". In such a score panel, the inner score line is generally provided to add strength to the end.
The outer score line, on the other hand, usually defines the perimeter of the opening which is formed when the end is opened. The outer score line generally includes a score groove formed in the upper surface of the end. This score groove terminates at a score residual region which is formed between the bottom of the score groove and the lower surface of the end. The thickness of the score residual is dictated by the depth of the score groove. When the end is opened, the score residual is ruptured, thus allowing the score panel to deflect into the can. The outer score line, thus, actually defines the shape of the score panel.
In one popular type of can end, the beginning portion and end portion of the score profile are spaced-apart. This spaced-apart region does not rupture during opening of the score panel and acts to retain the score panel on the can end after the primary score line has been ruptured. In this type can end, a separately formed tab member has an intermediate portion thereof riveted to a central portion of the can end at a position on the can end adjacent to the score panel. The tab member has a first end portion, generally referred to as a nose, which is initially positioned in contact with the score panel. The tab member has an opposite end portion which is generally formed in a ring-shaped configuration. In opening the can end, a user grasps the ring portion of the tab member and pulls upwardly causing the tab member to pivot about an axis which is typically adjacent to the rivet on the tab nose end side of the rivet. Thus, pulling up on the ring end portion causes the nose end portion to be urged against the score panel causing the score panel to rupture and eventually to pivotally deflect about an axis defined generally by the gap between the beginning and end portions of the score profile. The following U.S. patents disclose various can end configurations and are hereby incorporated by reference for all that is disclosed therein: U.S. Pat. No. Des. 364,807 issued Dec. 5, 1995 of Taylor; U.S. Pat. No. Des. 265,463 issued Jul. 20, 1996 of Hasegawa; U.S. Pat. No. Des. 267,393 issued Dec. 28, 1982 of Gruodis et al.; U.S. Pat. No. Des. 275,373 issued Sep. 4, 1984 of Brown et al.; U.S. Pat. No. 3,259,265 issued Jul. 5, 1966 of Stuart; U.S. Pat. No. 3,291,336 issued Dec. 13, 1966 of Fraze; U.S. Pat. No. 3,424,337 issued Jan. 28, 1969 of Von Stocker; U.S. Pat. No. 4,205,760 issued Jun. 3, 1980 of Hasegawa; U.S. Pat. No. 4,210,257 issued Jul. 1, 1980 of Radtke; U.S. Pat. No. 4,465,204 issued Aug. 14, 1984 of Kaminski et al.; U.S. Pat. No. Des. 246,229 issued Nov. 1, 1977 of Saunders; U.S. Pat. No. Des. 250,933 issued Jan. 30, 1979 of Saunders;
U.S. Pat. No. Des. 262,517 issued Jan. 5, 1982 of Hayes; U.S. Pat. No. 4,175,670 issued Nov. 27, 1979 of Reynolds et al.; U.S. Pat. No. 4,266,685 issued May 12, 1981 of Lee, Jr.; U.S. Pat. No. 4,313,545 issued Feb. 2, 1982 of Maeda; U.S. Pat. No. 4,318,489 issued Mar. 9, 1982 of Snyder et al.; U.S. Pat. No. 4,733,793 issued Mar. 29, 1988 of Moen et al.; U.S. Pat. No. 4,804,104 issued Feb. 14, 1989 of Moen et al.; U.S. Pat. No. 5,555,992 issued Sep. 17, 1996 of Sedgeley; U.S. patent application Ser. No. 08/593,035 filed Feb. 23, 1996 for CAN END WITH EMBOSS AND DEBOSS SCORE PANEL STIFFENING BEADS of Tim L. Turner and Robert L. Hurst and U.S. Design patent application Ser. No. 29/051,035 filed Feb. 23, 1996 for CAN END (design) of Robert L. Hurst and Tim L. Turner.
Score panel design requires a careful balancing of design parameters. In particular, the thickness of the score residual must be carefully chosen to ensure proper operation of the can end. If a designer selects a score residual which is too thin, the resulting can ends are subject to being ruptured during the production and during packaging and shipping operations. On the other hand, if the score residual is too thick, excessive force may be required to rupture the score.
It has been found that, in many cases, even can ends formed with an optimal score residual thickness may display certain problems. Specifically, it has been found that, when the score residual is sufficiently thin to allow proper opening, the score line residual sometimes ruptures too quickly, causing the score panel to rapidly move into contact with the beverage contained in the can. This, in turn, may cause a portion of the beverage to splash out of the can in an undesirable manner when the can is opened. Further, if the beverage in the can is a carbonated beverage, the rapid movement of the score panel may also cause the beverage to foam excessively in an undesirable manner.
Thus, it would be generally desirable to provide a can end which overcomes these problems associated with opening characteristics.